1. Field of the Invention
The present invention relates to a radiation detector, a radiographic imaging device and a radiographic imaging system. The present invention particularly relates to a radiation detector that accumulates charges generated due to irradiation of radiation, and detects electric signals corresponding to the accumulated charges as data expressing an image, a radiographic imaging device that employs the radiation detector to image radiographic images, and a radiographic imaging system.
2. Description of the Related Art
Radiographic imaging devices for imaging radiographic images are known in which a radiation detector detects radiation that has been irradiated from a radiation irradiation device and has passed through an imaging subject. The radiation detector of such a radiographic imaging device is configured with plural pixels disposed in a matrix. Each of the pixels includes a sensor portion, such as a photoelectric conversion element, that generates charges when irradiated with radiation or illuminated with light that has been converted from radiation, and a switching element that reads the charges generated in the sensor portion. The radiographic imaging device performs radiographic imaging by accumulating charges generated according to irradiated radiation, and detecting (reading) electric signals corresponding to the accumulated charges, as data expressing a radiographic image.
As such radiographic imaging devices, apparatuses provided with technology to synchronize a timing of the irradiation of the radiation from the radiation irradiation device and, for example, a start timing and an end timing for charge accumulation by the radiation detector. In such technology, radiation is detected based on the charges (electric signals) generated in the sensor portion due to irradiated radiation, in order to start or stop the accumulation of charges by the radiation detector.
As such technology, technology in which, for example, irradiated radiation is detected, and automatic exposure control (referred to below as AEC) that controls so as to stop the irradiation of radiation when an appropriate irradiation level has been reached, is known. For example, Japanese Patent Application Laid-Open (JP-A) No. 2005-147958 discloses a radiation detection apparatus, in which a portion of pixels above a gate line are provided with a monitoring photoelectric conversion element employed for AEC and an imaging photoelectric conversion element. In the above technology, the radiation detection apparatus performs AEC by using the monitoring photoelectric conversion elements.
Technology is also known in which radiographic imaging devices are provided with plural sensor portions (photoelectric conversion elements) within a single pixel. For example, in JP-A No. 2010-56396 discloses an X-ray detector in which, within a single pixel, a first sensor portion that detects light converted from low energy X-rays by a first scintillator provided on the X-ray irradiation side, and a second sensor portion that detects light converted from high energy X-rays by a second scintillator provided on the opposite side to the X-ray irradiation side, in order to obtain radiographic images from X-rays of different energies. In the technology described in JP-A No. 2010-56396, energy subtraction images are obtained by irradiating onto the second scintillator X-rays, that were attenuated as they passed through the first scintillator and further attenuated as they passed through a glass substrate. The second sensor portions then detect the light converted from these X-rays in the second scintillator.
In the technology described in JP-A No. 2005-147958, the radiation detection apparatus is provided with two different configurations (patterns) of pixels, namely a pattern with both the monitoring photoelectric conversion elements and the imaging photoelectric conversion elements, and a pattern with only the imaging photoelectric conversion elements.
However, when the radiation detector has pixels with greatly differing configurations (patterns), limitations in fabrication may occur. Further, when pixels with different configurations are provided, limitations of the specification of inspection devices for the radiation detection elements, issues may occur when testing the radiation detector. For example, pixels with greatly differing configurations may be detected as defective pixels (as with errors), and accurate examinations may not be performed.
Further, in the technology described in JP-A No. 2010-56396, the configurations of the pixels in the X-ray detector are the same. However, since the scintillators corresponding to the two respective sensor portions provided within a single pixel are different from each other, issue may arise when radiation irradiation detection is attempted. In the technology described in JP-A No. 2010-56396, the first sensor portions output charges (image data) based on light that has been converted from radiation by the first scintillator, and the second sensor portions for obtaining energy subtraction images output charges (energy subtraction data) based on light that has been converted by the second scintillator from X-rays attenuated by passing both through the first scintillator and through the glass substrate. The X-rays corresponding to the first sensor portions and the second sensor portions accordingly differ from each other. Therefore, the data output from the first sensor portions and the data output from the second sensor portions are data having different characteristics from each other. Accordingly, when radiation irradiation detection is attempted using the technology of JP-A No. 2010-56396, reduction in detection precision may occur, and there are cases in which it is preferable not to apply the technology of JP-A No. 2010-56396 for radiation detection.